proto_arp.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2009, 2010 Daniel Borkmann.
   5  * Subject to the GPL, version 2.
   6  */
   7
   8 #include <stdint.h>
   9 #include <netinet/in.h>    /* for ntohs() */
  10
  11 #include "proto.h"
  12 #include "protos.h"
  13 #include "dissector_eth.h"
  14 #include "pkt_buff.h"
  15 #include "built_in.h"
  16
  17 struct arphdr {
  18         uint16_t ar_hrd;   /* format of hardware address */
  19         uint16_t ar_pro;   /* format of protocol address */
  20         uint8_t ar_hln;    /* length of hardware address */
  21         uint8_t ar_pln;    /* length of protocol address */
  22         uint16_t ar_op;    /* ARP opcode (command)       */
  23         uint8_t ar_sha[6]; /* sender hardware address    */
  24         uint8_t ar_sip[4]; /* sender IP address          */
  25         uint8_t ar_tha[6]; /* target hardware address    */
  26         uint8_t ar_tip[4]; /* target IP address          */
  27 } __packed;
  28
  29 #define ARPOP_REQUEST   1  /* ARP request                */
  30 #define ARPOP_REPLY     2  /* ARP reply                  */
  31 #define ARPOP_RREQUEST  3  /* RARP request               */
  32 #define ARPOP_RREPLY    4  /* RARP reply                 */
  33 #define ARPOP_InREQUEST 8  /* InARP request              */
  34 #define ARPOP_InREPLY   9  /* InARP reply                */
  35 #define ARPOP_NAK       10 /* (ATM)ARP NAK               */
  36
  37 static void arp(struct pkt_buff *pkt)
  38 {
  39         char *opcode = NULL;
  40         struct arphdr *arp = (struct arphdr *) pkt_pull(pkt, sizeof(*arp));
  41
  42         if (arp == NULL)
  43                 return;
  44
  45         switch (ntohs(arp->ar_op)) {
  46         case ARPOP_REQUEST:
  47                 opcode = "ARP request";
  48                 break;
  49         case ARPOP_REPLY:
  50                 opcode = "ARP reply";
  51                 break;
  52         case ARPOP_RREQUEST:
  53                 opcode = "RARP request";
  54                 break;
  55         case ARPOP_RREPLY:
  56                 opcode = "RARP reply";
  57                 break;
  58         case ARPOP_InREQUEST:
  59                 opcode = "InARP request";
  60                 break;
  61         case ARPOP_InREPLY:
  62                 opcode = "InARP reply";
  63                 break;
  64         case ARPOP_NAK:
  65                 opcode = "(ATM) ARP NAK";
  66                 break;
  67         default:
  68                 opcode = "Unknown";
  69                 break;
  70         };
  71
  72         tprintf(" [ ARP ");
  73         tprintf("Format HA (%u), ", ntohs(arp->ar_hrd));
  74         tprintf("Format Proto (%u), ", ntohs(arp->ar_pro));
  75         tprintf("HA Len (%u), ", ntohs(arp->ar_hln));
  76         tprintf("Proto Len (%u), ", ntohs(arp->ar_pln));
  77         tprintf("Opcode (%u => %s)", ntohs(arp->ar_op), opcode);
  78         tprintf(" ]\n");
  79 }
  80
  81 static void arp_less(struct pkt_buff *pkt)
  82 {
  83         char *opcode = NULL;
  84         struct arphdr *arp = (struct arphdr *) pkt_pull(pkt, sizeof(*arp));
  85
  86         if (arp == NULL)
  87                 return;
  88
  89         switch (ntohs(arp->ar_op)) {
  90         case ARPOP_REQUEST:
  91                 opcode = "ARP request";
  92                 break;
  93         case ARPOP_REPLY:
  94                 opcode = "ARP reply";
  95                 break;
  96         case ARPOP_RREQUEST:
  97                 opcode = "RARP request";
  98                 break;
  99         case ARPOP_RREPLY:
 100                 opcode = "RARP reply";
 101                 break;
 102         case ARPOP_InREQUEST:
 103                 opcode = "InARP request";
 104                 break;
 105         case ARPOP_InREPLY:
 106                 opcode = "InARP reply";
 107                 break;
 108         case ARPOP_NAK:
 109                 opcode = "(ATM) ARP NAK";
 110                 break;
 111         default:
 112                 opcode = "Unknown";
 113                 break;
 114         };
 115
 116         tprintf(" Op %s", opcode);
 117 }
 118
 119 struct protocol arp_ops = {
 120         .key = 0x0806,
 121         .print_full = arp,
 122         .print_less = arp_less,
 123 };